Transformer by async generator (this might not work)

transformBy.ts

import { Duplex, ReadableOptions } from "stream";
export const createDeferredPromise = <T>() => {
  const res = {
    resolve: (_val: T) => {},
    reject: (_reason?: unknown) => {},
    promise: new Promise<T>((resolve, reject) => {
      res.resolve = resolve;
      res.reject = reject;
    }),
  };
  return res;
};

type InputGen = AsyncGenerator<{ chunk: unknown; encoding: unknown }, void>;

export function transformBy(
  asyncGeneratorFn: (input: InputGen) => AsyncGenerator<unknown, void>,
  options: ReadableOptions
) {
  let { promise, resolve } = createDeferredPromise<
    | { done: true; cb: () => void }
    | { done: false; chunk: unknown; encoding: string; cb: () => void }
  >();

  const asyncGenerator: InputGen = (async function* () {
    while (true) {
      const res = await promise;
      process.nextTick(res.cb);
      if (res.done) {
        return;
      }
      yield { chunk: res.chunk, encoding: res.encoding };
      ({ promise, resolve } = createDeferredPromise());
    }
  })();
  const write = (chunk: unknown, encoding: string, cb: () => void) => {
    resolve({ chunk, done: false, encoding, cb });
  };
  const final = (cb: () => void) => {
    resolve({ done: true, cb });
  };
  const optionsDuplex = {
    objectMode: true,
    autoDestroy: true,
    ...options,
  };
  Object.assign(optionsDuplex, final, write);
  return Duplex.from(asyncGeneratorFn(asyncGenerator), optionsDuplex);
}

from nodejs/node#38696